﻿using Mp4SubtitleParser;
using N_m3u8DL_RE.Common.Entity;
using N_m3u8DL_RE.Common.Util;
using System.Text;
using System.Text.RegularExpressions;

// https://github.com/canalplus/rx-player/blob/48d1f845064cea5c5a3546d2c53b1855c2be149d/src/parsers/manifest/smooth/get_codecs.ts
// https://github.dev/Dash-Industry-Forum/dash.js/blob/2aad3e79079b4de0bcd961ce6b4957103d98a621/src/mss/MssFragmentMoovProcessor.js
// https://github.com/yt-dlp/yt-dlp/blob/3639df54c3298e35b5ae2a96a25bc4d3c38950d0/yt_dlp/downloader/ism.py
// https://github.com/google/ExoPlayer/blob/a9444c880230d2c2c79097e89259ce0b9f80b87d/library/extractor/src/main/java/com/google/android/exoplayer2/video/HevcConfig.java#L38
// https://github.com/sannies/mp4parser/blob/master/isoparser/src/main/java/org/mp4parser/boxes/iso14496/part15/HevcDecoderConfigurationRecord.java
namespace N_m3u8DL_RE.Parser.Mp4;

public partial class MSSMoovProcessor
{
    [GeneratedRegex(@"\<KID\>(.*?)\<")]
    private static partial Regex KIDRegex();

    private static string StartCode = "00000001";
    private StreamSpec StreamSpec;
    private int TrackId = 2;
    private string FourCC;
    private string CodecPrivateData;
    private int Timesacle;
    private long Duration;
    private string Language => StreamSpec.Language ?? "und";
    private int Width => int.Parse((StreamSpec.Resolution ?? "0x0").Split('x').First());
    private int Height => int.Parse((StreamSpec.Resolution ?? "0x0").Split('x').Last());
    private string StreamType;
    private int Channels;
    private int BitsPerSample;
    private int SamplingRate;
    private int NalUnitLengthField;
    private long CreationTime = DateTimeOffset.UtcNow.ToUnixTimeSeconds();

    private bool IsProtection;
    private string ProtectionSystemId;
    private string ProtectionData;
    private string? ProtecitonKID;
    private string? ProtecitonKID_PR;
    private byte[] UnityMatrix
    {
        get
        {
            using var stream = new MemoryStream();
            using var writer = new BinaryWriter2(stream);
            writer.WriteInt(0x10000);
            writer.WriteInt(0);
            writer.WriteInt(0);
            writer.WriteInt(0);
            writer.WriteInt(0x10000);
            writer.WriteInt(0);
            writer.WriteInt(0);
            writer.WriteInt(0);
            writer.WriteInt(0x40000000);
            return stream.ToArray();
        }
    }
    private static byte TRACK_ENABLED = 0x1;
    private static byte TRACK_IN_MOVIE = 0x2;
    private static byte TRACK_IN_PREVIEW = 0x4;
    private static byte SELF_CONTAINED = 0x1;

    private static List<string> SupportedFourCC =
        ["HVC1", "HEV1", "AACL", "AACH", "EC-3", "H264", "AVC1", "DAVC", "AVC1", "TTML", "DVHE", "DVH1"];

    public MSSMoovProcessor(StreamSpec streamSpec)
    {
        this.StreamSpec = streamSpec;
        var data = streamSpec.MSSData!;
        this.NalUnitLengthField = data.NalUnitLengthField;
        this.CodecPrivateData = data.CodecPrivateData;
        this.FourCC = data.FourCC;
        this.Timesacle = data.Timesacle;
        this.Duration = data.Duration;
        this.StreamType = data.Type;
        this.Channels = data.Channels;
        this.SamplingRate = data.SamplingRate;
        this.BitsPerSample = data.BitsPerSample;
        this.IsProtection = data.IsProtection;
        this.ProtectionData = data.ProtectionData;
        this.ProtectionSystemId = data.ProtectionSystemID;

        // 需要手动生成CodecPrivateData
        if (string.IsNullOrEmpty(CodecPrivateData))
        {
            GenCodecPrivateDataForAAC();
        }

        // 解析KID
        if (IsProtection)
        {
            ExtractKID();
        }
    }

    private static string[] HEVC_GENERAL_PROFILE_SPACE_STRINGS = ["", "A", "B", "C"];
    private int SamplingFrequencyIndex(int samplingRate) => samplingRate switch
    {
        96000 => 0x0,
        88200 => 0x1,
        64000 => 0x2,
        48000 => 0x3,
        44100 => 0x4,
        32000 => 0x5,
        24000 => 0x6,
        22050 => 0x7,
        16000 => 0x8,
        12000 => 0x9,
        11025 => 0xA,
        8000 => 0xB,
        7350 => 0xC,
        _ => 0x0
    };

    private void GenCodecPrivateDataForAAC()
    {
        var objectType = 0x02; // AAC Main Low Complexity => object Type = 2
        var indexFreq = SamplingFrequencyIndex(SamplingRate);

        if (FourCC == "AACH")
        {
            // 4 bytes :     XXXXX         XXXX          XXXX             XXXX                  XXXXX      XXX   XXXXXXX
            //           ' ObjectType' 'Freq Index' 'Channels value'   'Extens Sampl Freq'  'ObjectType'  'GAS' 'alignment = 0'
            objectType = 0x05; // High Efficiency AAC Profile = object Type = 5 SBR
            var codecPrivateData = new byte[4];
            var extensionSamplingFrequencyIndex = SamplingFrequencyIndex(SamplingRate * 2); // in HE AAC Extension Sampling frequence
            // equals to SamplingRate*2
            // Freq Index is present for 3 bits in the first byte, last bit is in the second
            codecPrivateData[0] = (byte)((objectType << 3) | (indexFreq >> 1));
            codecPrivateData[1] = (byte)((indexFreq << 7) | (Channels << 3) | (extensionSamplingFrequencyIndex >> 1));
            codecPrivateData[2] = (byte)((extensionSamplingFrequencyIndex << 7) | (0x02 << 2)); // origin object type equals to 2 => AAC Main Low Complexity
            codecPrivateData[3] = 0x0; // alignment bits

            var arr16 = new ushort[2];
            arr16[0] = (ushort)((codecPrivateData[0] << 8) + codecPrivateData[1]);
            arr16[1] = (ushort)((codecPrivateData[2] << 8) + codecPrivateData[3]);

            // convert decimal to hex value
            this.CodecPrivateData = HexUtil.BytesToHex(BitConverter.GetBytes(arr16[0])).PadLeft(16, '0');
            this.CodecPrivateData += HexUtil.BytesToHex(BitConverter.GetBytes(arr16[1])).PadLeft(16, '0');
        }
        else if (FourCC.StartsWith("AAC")) 
        {
            // 2 bytes :     XXXXX         XXXX          XXXX              XXX
            //           ' ObjectType' 'Freq Index' 'Channels value'   'GAS = 000'
            var codecPrivateData = new byte[2];
            // Freq Index is present for 3 bits in the first byte, last bit is in the second
            codecPrivateData[0] = (byte)((objectType << 3) | (indexFreq >> 1));
            codecPrivateData[1] = (byte)((indexFreq << 7) | Channels << 3);
            // put the 2 bytes in an 16 bits array
            var arr16 = new ushort[1];
            arr16[0] = (ushort)((codecPrivateData[0] << 8) + codecPrivateData[1]);

            // convert decimal to hex value
            this.CodecPrivateData = HexUtil.BytesToHex(BitConverter.GetBytes(arr16[0])).PadLeft(16, '0');
        }
    }

    private void ExtractKID()
    {
        // playready
        if (ProtectionSystemId.ToUpper() == "9A04F079-9840-4286-AB92-E65BE0885F95")
        {
            var bytes = HexUtil.HexToBytes(ProtectionData.Replace("00", ""));
            var text = Encoding.ASCII.GetString(bytes);
            var kidBytes = Convert.FromBase64String(KIDRegex().Match(text).Groups[1].Value);
            // save kid for playready
            this.ProtecitonKID_PR = HexUtil.BytesToHex(kidBytes);
            // fix byte order
            var reverse1 = new[] { kidBytes[3], kidBytes[2], kidBytes[1], kidBytes[0] };
            var reverse2 = new[] { kidBytes[5], kidBytes[4], kidBytes[7], kidBytes[6] };
            Array.Copy(reverse1, 0, kidBytes, 0, reverse1.Length);
            Array.Copy(reverse2, 0, kidBytes, 4, reverse1.Length);
            this.ProtecitonKID = HexUtil.BytesToHex(kidBytes);
        }
        // widevine
        else if (ProtectionSystemId.ToUpper() == "EDEF8BA9-79D6-4ACE-A3C8-27DCD51D21ED")
        {
            throw new NotSupportedException();
        }
    }

    public static bool CanHandle(string fourCC) => SupportedFourCC.Contains(fourCC);

    private byte[] Box(string boxType, byte[] payload)
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteUInt(8 + (uint)payload.Length);
        writer.Write(boxType);
        writer.Write(payload);

        return stream.ToArray();
    }

    private byte[] FullBox(string boxType, byte version, uint flags, byte[] payload)
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.Write(version);
        writer.WriteUInt(flags, offset: 1);
        writer.Write(payload);

        return Box(boxType, stream.ToArray());
    }

    private byte[] GenSinf(string codec)
    {
        var frmaBox = Box("frma", Encoding.ASCII.GetBytes(codec));

        var sinfPayload = new List<byte>();
        sinfPayload.AddRange(frmaBox);

        var schmPayload = new List<byte>();
        schmPayload.AddRange(Encoding.ASCII.GetBytes("cenc")); // scheme_type 'cenc' => common encryption
        schmPayload.AddRange([0, 1, 0, 0]); // scheme_version Major version 1, Minor version 0
        var schmBox = FullBox("schm", 0, 0, schmPayload.ToArray());

        sinfPayload.AddRange(schmBox);

        var tencPayload = new List<byte>();
        tencPayload.AddRange([0, 0]);
        tencPayload.Add(0x1); // default_IsProtected
        tencPayload.Add(0x8); // default_Per_Sample_IV_size
        tencPayload.AddRange(HexUtil.HexToBytes(ProtecitonKID)); // default_KID
        // tencPayload.Add(0x8);// default_constant_IV_size
        // tencPayload.AddRange(new byte[8]);// default_constant_IV
        var tencBox = FullBox("tenc", 0, 0, tencPayload.ToArray());

        var schiBox = Box("schi", tencBox);
        sinfPayload.AddRange(schiBox);

        var sinfBox = Box("sinf", sinfPayload.ToArray());

        return sinfBox;
    }

    private byte[] GenFtyp()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.Write("isml"); // major brand
        writer.WriteUInt(1); // minor version
        writer.Write("iso5"); // compatible brand
        writer.Write("iso6"); // compatible brand
        writer.Write("piff"); // compatible brand
        writer.Write("msdh"); // compatible brand

        return Box("ftyp", stream.ToArray());
    }

    private byte[] GenMvhd()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteULong(CreationTime); // creation_time
        writer.WriteULong(CreationTime); // modification_time
        writer.WriteUInt(Timesacle); // timescale
        writer.WriteULong(Duration); // duration
        writer.WriteUShort(1, padding: 2); // rate
        writer.WriteByte(1, padding: 1); // volume
        writer.WriteUShort(0); // reserved
        writer.WriteUInt(0);
        writer.WriteUInt(0);

        writer.Write(UnityMatrix);

        writer.WriteUInt(0); // pre defined
        writer.WriteUInt(0);
        writer.WriteUInt(0);
        writer.WriteUInt(0);
        writer.WriteUInt(0);
        writer.WriteUInt(0);

        writer.WriteUInt(0xffffffff); // next track id


        return FullBox("mvhd", 1, 0, stream.ToArray());
    }

    private byte[] GenTkhd()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteULong(CreationTime); // creation_time
        writer.WriteULong(CreationTime); // modification_time
        writer.WriteUInt(TrackId); // track id
        writer.WriteUInt(0); // reserved
        writer.WriteULong(Duration); // duration
        writer.WriteUInt(0); // reserved
        writer.WriteUInt(0);
        writer.WriteShort(0); // layer
        writer.WriteShort(0); // alternate group
        writer.WriteByte(StreamType == "audio" ? (byte)1 : (byte)0, padding: 1); // volume
        writer.WriteUShort(0); // reserved

        writer.Write(UnityMatrix);

        writer.WriteUShort(Width, padding: 2); // width
        writer.WriteUShort(Height, padding: 2); // height

        return FullBox("tkhd", 1, (uint)TRACK_ENABLED | TRACK_IN_MOVIE | TRACK_IN_PREVIEW, stream.ToArray());
    }


    private byte[] GenMdhd()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteULong(CreationTime); // creation_time
        writer.WriteULong(CreationTime); // modification_time
        writer.WriteUInt(Timesacle); // timescale
        writer.WriteULong(Duration); // duration
        writer.WriteUShort((Language[0] - 0x60) << 10 | (Language[1] - 0x60) << 5 | (Language[2] - 0x60)); // language
        writer.WriteUShort(0); // pre defined

        return FullBox("mdhd", 1, 0, stream.ToArray());
    }

    private byte[] GenHdlr()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteUInt(0); // pre defined
        if (StreamType == "audio") writer.Write("soun");
        else if (StreamType == "video") writer.Write("vide");
        else if (StreamType == "text") writer.Write("subt");
        else throw new NotSupportedException();

        writer.WriteUInt(0); // reserved
        writer.WriteUInt(0);
        writer.WriteUInt(0);
        writer.Write($"{StreamSpec.GroupId ?? "RE Handler"}\0"); // name

        return FullBox("hdlr", 0, 0, stream.ToArray());
    }

    private byte[] GenMinf()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        var minfPayload = new List<byte>();
        if (StreamType == "audio")
        {
            var smhd = new List<byte>();
            smhd.Add(0); smhd.Add(0); // balance
            smhd.Add(0); smhd.Add(0); // reserved

            minfPayload.AddRange(FullBox("smhd", 0, 0, smhd.ToArray())); // Sound Media Header
        }
        else if (StreamType == "video")
        {
            var vmhd = new List<byte>();
            vmhd.Add(0); vmhd.Add(0); // graphics mode
            vmhd.Add(0); vmhd.Add(0); vmhd.Add(0); vmhd.Add(0); vmhd.Add(0); vmhd.Add(0);// opcolor

            minfPayload.AddRange(FullBox("vmhd", 0, 1, vmhd.ToArray())); // Video Media Header
        }
        else if (StreamType == "text")
        {
            minfPayload.AddRange(FullBox("sthd", 0, 0, [])); // Subtitle Media Header
        }
        else
        {
            throw new NotSupportedException();
        }

        var drefPayload = new List<byte>();
        drefPayload.Add(0); drefPayload.Add(0); drefPayload.Add(0); drefPayload.Add(1); // entry count
        drefPayload.AddRange(FullBox("url ", 0, SELF_CONTAINED, [])); // Data Entry URL Box

        var dinfPayload = FullBox("dref", 0, 0, drefPayload.ToArray()); // Data Reference Box
        minfPayload.AddRange(Box("dinf", dinfPayload.ToArray())); // Data Information Box

        return minfPayload.ToArray();
    }

    private byte[] GenEsds(byte[] audioSpecificConfig)
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        // ESDS length = esds box header length (= 12) +
        //               ES_Descriptor header length (= 5) +
        //               DecoderConfigDescriptor header length (= 15) +
        //               decoderSpecificInfo header length (= 2) +
        //               AudioSpecificConfig length (= codecPrivateData length)
        // esdsLength = 34 + len(audioSpecificConfig)

        // ES_Descriptor (see ISO/IEC 14496-1 (Systems))
        writer.WriteByte(0x03); // tag = 0x03 (ES_DescrTag)
        writer.WriteByte((byte)(20 + audioSpecificConfig.Length)); // size
        writer.WriteByte((byte)((TrackId & 0xFF00) >> 8)); // ES_ID = track_id
        writer.WriteByte((byte)(TrackId & 0x00FF));
        writer.WriteByte(0); // flags and streamPriority

        // DecoderConfigDescriptor (see ISO/IEC 14496-1 (Systems))
        writer.WriteByte(0x04); // tag = 0x04 (DecoderConfigDescrTag)
        writer.WriteByte((byte)(15 + audioSpecificConfig.Length)); // size
        writer.WriteByte(0x40); // objectTypeIndication = 0x40 (MPEG-4 AAC)
        writer.WriteByte((0x05 << 2) | (0 << 1) | 1); // reserved = 1
        writer.WriteByte(0xFF); // buffersizeDB = undefined
        writer.WriteByte(0xFF); 
        writer.WriteByte(0xFF);

        var bandwidth = StreamSpec.Bandwidth!;
        writer.WriteByte((byte)((bandwidth & 0xFF000000) >> 24)); // maxBitrate
        writer.WriteByte((byte)((bandwidth & 0x00FF0000) >> 16));
        writer.WriteByte((byte)((bandwidth & 0x0000FF00) >> 8));
        writer.WriteByte((byte)(bandwidth  & 0x000000FF));
        writer.WriteByte((byte)((bandwidth & 0xFF000000) >> 24)); // avgbitrate
        writer.WriteByte((byte)((bandwidth & 0x00FF0000) >> 16)); 
        writer.WriteByte((byte)((bandwidth & 0x0000FF00) >> 8));
        writer.WriteByte((byte)(bandwidth  & 0x000000FF));

        // DecoderSpecificInfo (see ISO/IEC 14496-1 (Systems))
        writer.WriteByte(0x05); // tag = 0x05 (DecSpecificInfoTag)
        writer.WriteByte((byte)audioSpecificConfig.Length); // size
        writer.Write(audioSpecificConfig); // AudioSpecificConfig bytes

        return FullBox("esds", 0, 0, stream.ToArray());
    }

    private byte[] GetSampleEntryBox()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteByte(0); // reserved
        writer.WriteByte(0);
        writer.WriteByte(0);
        writer.WriteByte(0);
        writer.WriteByte(0);
        writer.WriteByte(0);
        writer.WriteUShort(1); // data reference index

        if (StreamType == "audio")
        {
            writer.WriteUInt(0); // reserved2
            writer.WriteUInt(0);
            writer.WriteUShort(Channels); // channels
            writer.WriteUShort(BitsPerSample); // bits_per_sample
            writer.WriteUShort(0); // pre defined
            writer.WriteUShort(0); // reserved3
            writer.WriteUShort(SamplingRate, padding: 2); // sampling_rate

            var audioSpecificConfig = HexUtil.HexToBytes(CodecPrivateData);
            var esdsBox = GenEsds(audioSpecificConfig);
            writer.Write(esdsBox);

            if (FourCC.StartsWith("AAC")) 
            {
                if (IsProtection)
                {
                    var sinfBox = GenSinf("mp4a");
                    writer.Write(sinfBox);
                    return Box("enca", stream.ToArray()); // Encrypted Audio
                }
                return Box("mp4a", stream.ToArray());
            }
            if (FourCC == "EC-3")
            {
                if (IsProtection)
                {
                    var sinfBox = GenSinf("ec-3");
                    writer.Write(sinfBox);
                    return Box("enca", stream.ToArray()); // Encrypted Audio
                }
                return Box("ec-3", stream.ToArray());
            }
        }
        else if (StreamType == "video")
        {
            writer.WriteUShort(0); // pre defined
            writer.WriteUShort(0); // reserved
            writer.WriteUInt(0); // pre defined
            writer.WriteUInt(0);
            writer.WriteUInt(0);
            writer.WriteUShort(Width); // width
            writer.WriteUShort(Height); // height
            writer.WriteUShort(0x48, padding: 2); // horiz resolution 72 dpi
            writer.WriteUShort(0x48, padding: 2); // vert resolution 72 dpi
            writer.WriteUInt(0); // reserved
            writer.WriteUShort(1); // frame count
            for (int i = 0; i < 32; i++) // compressor name
            {
                writer.WriteByte(0);
            }
            writer.WriteUShort(0x18); // depth
            writer.WriteUShort(65535); // pre defined

            var codecPrivateData = HexUtil.HexToBytes(CodecPrivateData);

            if (FourCC is "H264" or "AVC1" or "DAVC")
            {
                var arr = CodecPrivateData.Split([StartCode], StringSplitOptions.RemoveEmptyEntries);
                var sps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] & 0x1F) == 7));
                var pps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] & 0x1F) == 8));
                // make avcC
                var avcC = GetAvcC(sps, pps);
                writer.Write(avcC);
                if (IsProtection)
                {
                    var sinfBox = GenSinf("avc1");
                    writer.Write(sinfBox);
                    return Box("encv", stream.ToArray()); // Encrypted Video
                }
                return Box("avc1", stream.ToArray()); // AVC Simple Entry
            }
            if (FourCC is "HVC1" or "HEV1")
            {
                var arr = CodecPrivateData.Split([StartCode], StringSplitOptions.RemoveEmptyEntries);
                var vps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] >> 1) == 0x20));
                var sps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] >> 1) == 0x21));
                var pps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] >> 1) == 0x22));
                // make hvcC
                var hvcC = GetHvcC(sps, pps, vps);
                writer.Write(hvcC);
                if (IsProtection)
                {
                    var sinfBox = GenSinf("hvc1");
                    writer.Write(sinfBox);
                    return Box("encv", stream.ToArray()); // Encrypted Video
                }
                return Box("hvc1", stream.ToArray()); // HEVC Simple Entry
            }
            // 杜比视界也按照hevc处理
            if (FourCC is "DVHE" or "DVH1")
            {
                var arr = CodecPrivateData.Split([StartCode], StringSplitOptions.RemoveEmptyEntries);
                var vps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] >> 1) == 0x20));
                var sps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] >> 1) == 0x21));
                var pps = HexUtil.HexToBytes(arr.First(x => (HexUtil.HexToBytes(x[0..2])[0] >> 1) == 0x22));
                // make hvcC
                var hvcC = GetHvcC(sps, pps, vps, "dvh1");
                writer.Write(hvcC);
                if (IsProtection)
                {
                    var sinfBox = GenSinf("dvh1");
                    writer.Write(sinfBox);
                    return Box("encv", stream.ToArray()); // Encrypted Video
                }
                return Box("dvh1", stream.ToArray()); // HEVC Simple Entry
            }

            throw new NotSupportedException();
        }
        else if (StreamType == "text")
        {
            if (FourCC == "TTML")
            {
                writer.Write("http://www.w3.org/ns/ttml\0"); // namespace
                writer.Write("\0"); // schema location
                writer.Write("\0"); // auxilary mime types(??)
                return Box("stpp", stream.ToArray()); // TTML Simple Entry
            }
            throw new NotSupportedException();
        }
        else
        {
            throw new NotSupportedException();
        }

        throw new NotSupportedException();
    }

    private byte[] GetAvcC(byte[] sps, byte[] pps)
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteByte(1); // configuration version
        writer.Write(sps[1..4]); // avc profile indication + profile compatibility + avc level indication
        writer.WriteByte((byte)(0xfc | (NalUnitLengthField - 1))); // complete representation (1) + reserved (11111) + length size minus one
        writer.WriteByte(1); // reserved (0) + number of sps (0000001)
        writer.WriteUShort(sps.Length);
        writer.Write(sps);
        writer.WriteByte(1); // number of pps
        writer.WriteUShort(pps.Length);
        writer.Write(pps);

        return Box("avcC", stream.ToArray()); // AVC Decoder Configuration Record
    }

    private byte[] GetHvcC(byte[] sps, byte[] pps, byte[] vps, string code = "hvc1")
    {
        var oriSps = new List<byte>(sps);
        // https://www.itu.int/rec/dologin.asp?lang=f&id=T-REC-H.265-201504-S!!PDF-E&type=items
        // Read generalProfileSpace, generalTierFlag, generalProfileIdc,
        // generalProfileCompatibilityFlags, constraintBytes, generalLevelIdc
        // from sps
        var encList = new List<byte>();
        /**
         * 处理payload, 有00 00 03 0,1,2,3的情况 统一换成00 00 XX 即丢弃03
         * 注意：此处采用的逻辑是直接简单粗暴地判断列表末尾3字节，如果是0x000003就删掉最后的0x03，可能会导致以下情况
         * 00 00 03 03 03 03 03 01 会被直接处理成 => 00 00 01
         * 此处经过测试只有直接跳过才正常，如果处理成 00 00 03 03 03 03 01 是有问题的
         *
         * 测试的数据如下：
         *   原始：42 01 01 01 60 00 00 03 00 90 00 00 03 00 00 03 00 96 a0 01 e0 20 06 61 65 95 9a 49 30 bf fc 0c 7c 0c 81 a8 08 08 08 20 00 00 03 00 20 00 00 03 03 01
         * 处理后：42 01 01 01 60 00 00 00 90 00 00 00 00 00 96 A0 01 E0 20 06 61 65 95 9A 49 30 BF FC 0C 7C 0C 81 A8 08 08 08 20 00 00 00 20 00 00 01
         */
        using (var _reader = new BinaryReader(new MemoryStream(sps)))
        {
            while (_reader.BaseStream.Position < _reader.BaseStream.Length)
            {
                encList.Add(_reader.ReadByte());
                if (encList is [.., 0x00, 0x00, 0x03])
                {
                    encList.RemoveAt(encList.Count - 1);
                }
            }
        }
        sps = encList.ToArray();

        using var reader = new BinaryReader2(new MemoryStream(sps));
        reader.ReadBytes(2); // Skip 2 bytes unit header
        var firstByte = reader.ReadByte();
        var maxSubLayersMinus1 = (firstByte & 0xe) >> 1;
        var nextByte = reader.ReadByte();
        var generalProfileSpace = (nextByte & 0xc0) >> 6;
        var generalTierFlag = (nextByte & 0x20) >> 5;
        var generalProfileIdc = nextByte & 0x1f;
        var generalProfileCompatibilityFlags = reader.ReadUInt32();
        var constraintBytes = reader.ReadBytes(6);
        var generalLevelIdc = reader.ReadByte();

        /*var skipBit = 0;
        for (int i = 0; i < maxSubLayersMinus1; i++)
        {
            skipBit += 2; // sub_layer_profile_present_flag sub_layer_level_present_flag
        }
        if (maxSubLayersMinus1 > 0)
        {
            for (int i = maxSubLayersMinus1; i < 8; i++)
            {
                skipBit += 2; // reserved_zero_2bits
            }
        }
        for (int i = 0; i < maxSubLayersMinus1; i++)
        {
            skipBit += 2; // sub_layer_profile_present_flag sub_layer_level_present_flag
        }*/

        // 生成编码信息
        var codecs = code +
                     $".{HEVC_GENERAL_PROFILE_SPACE_STRINGS[generalProfileSpace]}{generalProfileIdc}" +
                     $".{Convert.ToString(generalProfileCompatibilityFlags, 16)}" +
                     $".{(generalTierFlag == 1 ? 'H' : 'L')}{generalLevelIdc}" +
                     $".{HexUtil.BytesToHex(constraintBytes.Where(b => b != 0).ToArray())}";
        StreamSpec.Codecs = codecs;


        ///////////////////////


        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        // var reserved1 = 0xF;

        writer.WriteByte(1); // configuration version
        writer.WriteByte((byte)((generalProfileSpace << 6) + (generalTierFlag == 1 ? 0x20 : 0) | generalProfileIdc)); // general_profile_space + general_tier_flag + general_profile_idc
        writer.WriteUInt(generalProfileCompatibilityFlags); // general_profile_compatibility_flags
        writer.Write(constraintBytes); // general_constraint_indicator_flags
        writer.WriteByte((byte)generalProfileIdc); // general_level_idc
        writer.WriteUShort(0xf000); // reserved + min_spatial_segmentation_idc
        writer.WriteByte(0xfc); // reserved + parallelismType
        writer.WriteByte(0 | 0xfc); // reserved + chromaFormat 
        writer.WriteByte(0 | 0xf8); // reserved + bitDepthLumaMinus8
        writer.WriteByte(0 | 0xf8); // reserved + bitDepthChromaMinus8
        writer.WriteUShort(0); // avgFrameRate
        writer.WriteByte((byte)(0 << 6 | 0 << 3 | 0 << 2 | (NalUnitLengthField - 1))); // constantFrameRate + numTemporalLayers + temporalIdNested + lengthSizeMinusOne
        writer.WriteByte(0x03); // numOfArrays (vps sps pps)
            
        sps = oriSps.ToArray();
        writer.WriteByte(0x20); // array_completeness + reserved + NAL_unit_type
        writer.WriteUShort(1); // numNalus 
        writer.WriteUShort(vps.Length);
        writer.Write(vps);
        writer.WriteByte(0x21);
        writer.WriteUShort(1); // numNalus
        writer.WriteUShort(sps.Length);
        writer.Write(sps);
        writer.WriteByte(0x22); 
        writer.WriteUShort(1); // numNalus
        writer.WriteUShort(pps.Length);
        writer.Write(pps);

        return Box("hvcC", stream.ToArray()); // HEVC Decoder Configuration Record
    }

    private byte[] GetStsd()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteUInt(1); // entry count
        var sampleEntryData = GetSampleEntryBox();
        writer.Write(sampleEntryData);

        return stream.ToArray();
    }

    private byte[] GetMehd()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteULong(Duration);

        return FullBox("mehd", 1, 0, stream.ToArray()); // Movie Extends Header Box
    }
    private byte[] GetTrex()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        writer.WriteUInt(TrackId); // track id
        writer.WriteUInt(1); // default sample description index
        writer.WriteUInt(0); // default sample duration
        writer.WriteUInt(0); // default sample size
        writer.WriteUInt(0); // default sample flags

        return FullBox("trex", 0, 0, stream.ToArray()); // Track Extends Box
    }

    private byte[] GenPsshBoxForPlayReady()
    {
        using var _stream = new MemoryStream();
        using var _writer = new BinaryWriter2(_stream);
        var sysIdData = HexUtil.HexToBytes(ProtectionSystemId.Replace("-", ""));
        var psshData = HexUtil.HexToBytes(ProtectionData);

        _writer.Write(sysIdData);  // SystemID 16 bytes
        _writer.WriteUInt(psshData.Length); // Size of Data 4 bytes
        _writer.Write(psshData); // Data
        var psshBox = FullBox("pssh", 0, 0, _stream.ToArray());
        return psshBox;
    }

    private byte[] GenPsshBoxForWideVine()
    {
        using var _stream = new MemoryStream();
        using var _writer = new BinaryWriter2(_stream);
        var sysIdData = HexUtil.HexToBytes("edef8ba9-79d6-4ace-a3c8-27dcd51d21ed".Replace("-", ""));
        // var kid = HexUtil.HexToBytes(ProtecitonKID);

        _writer.Write(sysIdData);  // SystemID 16 bytes
        var psshData = HexUtil.HexToBytes($"08011210{ProtecitonKID}1A046E647265220400000000");
        _writer.WriteUInt(psshData.Length); // Size of Data 4 bytes
        _writer.Write(psshData); // Data
        var psshBox = FullBox("pssh", 0, 0, _stream.ToArray());
        return psshBox;
    }

    private byte[] GenMoof()
    {
        using var stream = new MemoryStream();
        using var writer = new BinaryWriter2(stream);

        // make senc
        writer.WriteUInt(1); // sample_count
        writer.Write(new byte[8]); // 8 bytes IV

        var sencBox = FullBox("senc", 1, 0, stream.ToArray());

        var moofBox = Box("moof", sencBox); // Movie Extends Box

        return moofBox;
    }

    public byte[] GenHeader(byte[] firstSegment)
    {
        new MP4Parser()
            .Box("moof", MP4Parser.Children)
            .Box("traf", MP4Parser.Children)
            .FullBox("tfhd", box =>
            {
                TrackId = (int)box.Reader.ReadUInt32();
            })
            .Parse(firstSegment);

        return GenHeader();
    }

    public byte[] GenHeader()
    {
        using var stream = new MemoryStream();

        var ftyp = GenFtyp(); // File Type Box
        stream.Write(ftyp);

        var moovPayload = GenMvhd(); // Movie Header Box

        var trakPayload = GenTkhd(); // Track Header Box

        var mdhdPayload = GenMdhd(); // Media Header Box

        var hdlrPayload = GenHdlr(); // Handler Reference Box

        var mdiaPayload = mdhdPayload.Concat(hdlrPayload).ToArray();

        var minfPayload = GenMinf();


        var sttsPayload = new byte[] { 0, 0, 0, 0 }; // entry count
        var stblPayload = FullBox("stts", 0, 0, sttsPayload); // Decoding Time to Sample Box

        var stscPayload = new byte[] { 0, 0, 0, 0 }; // entry count
        var stscBox = FullBox("stsc", 0, 0, stscPayload); // Sample To Chunk Box

        var stcoPayload = new byte[] { 0, 0, 0, 0 }; // entry count
        var stcoBox = FullBox("stco", 0, 0, stcoPayload); // Chunk Offset Box

        var stszPayload = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0 }; // sample size, sample count
        var stszBox = FullBox("stsz", 0, 0, stszPayload); // Sample Size Box

        var stsdPayload = GetStsd();
        var stsdBox = FullBox("stsd", 0, 0, stsdPayload); // Sample Description Box

        stblPayload = stblPayload.Concat(stscBox).Concat(stcoBox).Concat(stszBox).Concat(stsdBox).ToArray();


        var stblBox = Box("stbl", stblPayload); // Sample Table Box
        minfPayload = minfPayload.Concat(stblBox).ToArray();

        var minfBox = Box("minf", minfPayload); // Media Information Box
        mdiaPayload = mdiaPayload.Concat(minfBox).ToArray();

        var mdiaBox = Box("mdia", mdiaPayload); // Media Box
        trakPayload = trakPayload.Concat(mdiaBox).ToArray();

        var trakBox = Box("trak", trakPayload); // Track Box
        moovPayload = moovPayload.Concat(trakBox).ToArray();

        var mvexPayload = GetMehd();
        var trexBox = GetTrex();
        mvexPayload = mvexPayload.Concat(trexBox).ToArray();

        var mvexBox = Box("mvex", mvexPayload); // Movie Extends Box
        moovPayload = moovPayload.Concat(mvexBox).ToArray();

        if (IsProtection)
        {
            var psshBox1 = GenPsshBoxForPlayReady();
            var psshBox2 = GenPsshBoxForWideVine();
            moovPayload = moovPayload.Concat(psshBox1).Concat(psshBox2).ToArray();
        }

        var moovBox = Box("moov", moovPayload); // Movie Box

        stream.Write(moovBox);

        // var moofBox = GenMoof(); // Movie Extends Box
        // stream.Write(moofBox);

        return stream.ToArray();
    }
}